Vehicles of a wide variety, including automobiles, personal trucks, motorcycles and motor bikes have quickly become the world's most popular form of daily transportation and today are both manufactured and sold at ever increasing rates. The popularity of the personal vehicle is directly related to its propulsion system, the internal combustion engine, which yields relatively efficient and inexpensive power. Harnessing and manipulating this power, however, does not come without any detrimental effects. The result of each power producing explosion occurring within the internal combustion engine is exhaust, which includes a significant combination of both noise and air pollution. Efforts to eliminate or minimize the after combustion polluting effects of internal combustion engines have become as important today as those efforts which seek to maximize the output force these engines produce.
Two separate units, a muffler and a catalytic converter, are conventionally employed on today's automobiles to minimize emission noise and air pollution, respectively, at two separate stages of the exhaust stream. Mufflers typically are designed in one of three ways: (a) with staggered baffles; (b) with sound defeating angling; or (c) with fiberglass packing. Staggered baffled mufflers are the most commonly used in the automobile industry because they are efficient, inexpensive and easy to manufacture.
Catalytic converters, on the other hand, are typically designed in two ways: (a) with a honeycomb material; or (b) with beads. Both the honeycomb material and the beads are coated with a catalytic substance which causes the undesirable and harmful compounds in the exhaust gas emission stream to be converted in a predetermined catalytic reaction into harmless components.
Hence, treatment of noise and air pollution within an exhaust gas emission stream is accomplished conventionally by these two separate devices, each acting independently of one another. Accordingly, the conventional catalytic converter does not substantially silence exhausting emissions and the conventional muffler does not catalytically treat exhausting emissions.
The need to simultaneously reduce both noise and polluting emissions is of particular importance to manufacturers of small internal combustion engines, such as those for tractors, lawn and yard maintenance equipment, motor bikes, scooters, snow and leaf blowers and other power equipment where there is an increasing demand for reducing emissions and noise levels Most of such small engines are equipped with a small muffler to control noise levels. Since existing small engine manufacturers do not wish to change muffler design, a typical design for such a unit is to include a small metal substrate catalyst for controlling harmful emissions in the existing muffler. In that case, the muffler and catalyst are not independent of each other.